Lubricant composition and method of making the same



United States Patent ice 3,114,712 LUBRICANT COMPOSITION AND METHOD OF MAKING THE SAME Giinter Spengler, Munich, Germany, and Josef Giinsheimer, Greenwich, Conn, assignors to Alpha-Molykote Corporation, Stamford, Conn.

No Drawing. Filed Nov. 5, 1959, Ser.No. 851,025 Claims priority, application Germany Nov. 8, 1958 7 Claims. (Cl. 252--46.4)

This invention relates to lubricant additives, lubricants, and methods of making the same, and relates in particular to lubricant additives and lubricants containing compounds of molybdenum, and methods of making the same.

The good lubricant properties of some inorganic molybdenum compounds, such as molybdenum disulfide, are well known. However, the practical exploitation of these compounds as lubricant additives is hindered by their insolubility and the consequent necessity of using the compounds by suspending them, finely divided, in a lubricating oil. The subdivision of the compounds and their suspension is complicated by problems of oxidation and by the high density of the compounds.

Attempts have been made to produce oil soluble organic molybdenum compounds, preferably also containing sulfur in the molecule. These products usually have the drawback of being contaminated with corrosive agents (e.g. halogens or halides) used in their synthesis, or of being oil-insoluble Without the additional use of solubilizing agents, or of having such low thermal stability that supplemental oil-soluble thermal-stabilizing additives must be used with them. The synthesis of the organic molybdenum compounds is often complex.

According to the present invention, the lubricating properties of both synthetic and mineral lubricants, particularly the load capacities of the lubricants, can be greatly improved by the addition thereto of novel organic molybdenum-containing substances which are thermally stable, fully oil soluble in all proportions without the use of solubilizing agents, are easily prepared, and do not contain corrosive contaminants.

The new additives are solution of molybdates of organic nitrogen bases in mixtures of monothiophosphoric acid dialkyl esters and alkyldithiophosphoric acid dialkyl esters.

The organic molybdate salts are conveniently prepared by reacting molybdic acid with a primary, secondary, or tertiary aliphatic amine or with a heterocyclic nitrogen base. The reaction is conveniently carried out simply by warming the molybdic acid with the base until solution occurs. As aliphatic amines, methyl amine, ethyl amine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert.-butyl amine, namylamine, isoamylamine, Z-aminopentane, octylamine, etc., dimethylamine, diethylamine, di-n-propylamine, di-isopropylamine, the di-butylamines, trimethylamine, methyldiethylamine, triethylamine, dimethylethylamine, diethyl-n-propylamine, and tri-isopropylamine, etc., can be given in an exemplary, but not exclusive, listing. Aliphatic amines with as many as 18 carbon atoms in the nitrogen-attached carbon chains can be used. Heterocyclic nitrogen bases include pyrrole, isopyrrole, pyridine, indole, and bases having aliphatic side chains, such as 1-hydroxyethyl-2- heptadecenyl glyoxalidine,

The heterocyclic nitrogen bases may also conveniently be used as solvents for molybdate salts of aliphatic amines 3,114,712 Patented Dec. 1 .7, 1963 when combining salts with the thiophosphoric acid esters described below.

The thiophosphoric acid esters which are used to dissolve the organic molybdate salts are produced by reacting phosphorus pentasulfide and an alcohol according to:

The reaction is accomplished by mixing the reactants and warming gently to promote solution of the pentasulfide and evolution of hydrogen sulfide.

Aliphatic alcohols, both saturated and unsaturated, and having a chain length of from 8 to 20 carbon atoms, preferably 12-18 carbon atoms, are of particular usefulness in the reaction described above.

The thiophosphoric acid esters produced as described are then mixed with the organic molybdate salts first discussed, and the mixtures are heated gently to bring about solution. The solutions, which are at first deep red in color, change to green, and then to brown on heating. In preparing the solution, a molar excess of the esters is used. A molar ratio of esters to salts of at least two is preferably used, and the esters may predominate in as much as 6-fold ratio. The brown solution, or reaction product, is then added to a lubricating oil in amounts between 6-12 percent by weight, preferably 1()12 percent by weight, of the mixture. The nature of the lubricating oil is not critical, and both synthetic and mineral lubricating oils can be improved by the present additives.

The following specific examples are representative of the preparation of the lubricant additives of the invention.

Example 1 2.22 grams (0.01 mole) of finely pulverized P 8 were added to 6.5 gm. (0.05 mole) of octyl alcohol. H 5 was generated, and the reaction mixture was heated to complete the dissolving of the phosphorus pentasulfide.

In another vessel, 5.9 gm. (0.1 mole) of n-propylamine were diluted with 20 ml. of water. 8.1 gm. (0.05 mole) of molybdic acid were added and the mixture warmed until the acid had gone into solution. After cooling, ethanol was added to the solution until n-propylammonium-dimolybdate started to precipitate. The solution was refrigerated overnight and then filtered. The solid was washed with acetone and air-dried.

1.0 gm. of the n-propylammonium-dimolybdate was then dissolved in 3.0 gm. of 1-hydroxyethyl-2-heptadecenylglyoxalidin, with gentle heating until a clear solution was obtained. This solution was then mixed with the thiophosphoric acid esters first prepared and warmed until a brown solution resulted. Any traces of solids were then removed by filtering.

12 gm. of this mixture were dissolved in 88 gm. of mineral oil (Esso Necton and tested on a four-ball machine and an Almen-Wieland tester. The influence on the load capacity of the oil can be seen in the following table.

Lubricant Composition lfiur-Bali Load Capacity (kg) Almonacliine W1eland Tester Esso Necton 80 (no additive) 12 percent solution of additive of Example 1 in Esso Necton 80.

200 shaft breakage. 240/260 1,500 continuous operation passed. Final temperature C. Total Abrasion: 0.0223 g. Friction force at 1,500 kg. Load: 210 kg. at the end of continuous operation: 235 kg.

9 t gm. (0.05 mole) of a mixture of unsaturated alcohols having C C chains and an average molecular weight of 240. The P 3 was completely dissolved by warming. This solution was then mixed with a solution of 0.0025 mole of n-propylamoniumdimolybdate (prepared as in Example 1) dissolved, with warming, in 3.0 gm. of octyl amine. The mixed solutions were warmed until a brown solution was produced. Any undissolved solids were then filtered out through a frit.

12 gm. of this product were dissolved in 88 gm. of mineral oil (Esso Necton 80) and tested as before.

Four-Ball Load Capacity (kg.) Almen- Lubricant Composition Machine Wieland Tester Esso Necton 80 (no additive) 120/130 200 hsaft breakage. 12 percent solution of additive 240/260 1,500 continuous operation passed. Final temperature: 145 C. Total Abrasi0n:0.0148fg. Friction force at 1,500 kg. Load: 218 kg. at the end of continuous operation: 246 kg.

gt Example 1 in Esso Necton Although specific embodiments have been shown and described, it is to be understood that they are illustrative, and are not to be construed as limiting the scope and spirit of the invention.

What is claimed is:

1. A11 oil-soluble lubricant additive consisting essentially of an about equimolar mixture of a monothiophosphoric acid dialkyl ester of the formula and an alkyldithiophosphoric acid ester of the formula of molybdic acid and a primary-amino substituted aliphatic hydrocarbon having up to 18 carbon atoms.

3. An additive as in claim 1 where R is octyl.

4. A11 additive as in claim 1 wherein R is a mixture of unsaturated C C radicals derived from a corresponding mixture of unsaturated alcohols having an average molecular weight of about 240.

5. A lubricating composition of high load capacity consisting essentially of a mineral lubricating oil and an oil soluble additive as defined in claim 1, said additive being present as about 6-12 percent by weight of the oil and additive combined.

6. The method of making an oil-soluble lubricant additive which comprises dissolving phosphorus pentasulfide in an alcohol of the formula ROH, where R is an aliphatic hydrocarbon radical having from 8 to 18 carbon atoms, with evolution of hydrogen sulfide and formation of an about equimolar mixture of a monothiophosphoric acid dialkyl ester of the formula Ro OH and an alkyldithiophosphoric acid ester of the formula RO S where R has its earlier significance, and then dissolving in said mixture a salt of molybdic acid and a member of the group consisting of primary-, secondary-, and tertiaryamino substituted aliphatic hydrocarbons having up to 18 carbon atoms, pyrrole, isopyrrole, pyridine, indole, and lhydroxyethyl-Z-heptadecenyl glyoxalidine, the molar ratio of said phosphoric acid esters to said molybdic acid salt being at least two.

7. The method as in claim 6 wherein said salt is dissolved with gentle heating.

References Cited in the file of this patent UNITED STATES PATENTS 2,157,452 Humphreys May 9, 1939 2,167,867 Benning Aug. 1, 1939 2,753,306 Fields July 3, 1956 2,852,469 Hugel Sept. 16, 1958 2,866,732 Hofi et a1. Dec. 30, 1958 2,938,869 Hugel May 31, 1960 3,050,538 Hugel et al Aug. 21, 1962 

1. AN OIL-SOLUBLE LUBRICANT ADDITIVE CONSISTING ESSENTIALLY OF AN ABOUT EQUIMOLAR MIXTURE OF A MONOTHIOPHOSPHORIC ACID DIALKY ESTER OF THE FORMULA 